I was talking to a psychologist recently, who have been involved extensively in psychometric testing (not at QF). He thought it wasn't worth the paper/computer it's done on, and it makes no difference to the outcome. I believe him.
I asked another psychologist and she thought it was a load of rubbish too.
So, if the profession that developed it thinks it is rubbish, it probably is. It's not in their interest to bash it, is it.